SMITH & WESSON HAND EJECTOR ("NEW CENTURY") REVOLVERS:
The .455 S&W model actually ordered (by both Canada and Britain) during WWI was the Second Model Hand Ejector, but my references indicate that both Canada and Britain accepted a few First Model HE revolvers (also referred to as the "Triple Lock" Hand Ejector) which S&W had in stock and was thus able to ship immediately. One such First Model with a C-Broadarrow stamp illustrated in Law's book is s/n 5498.
The first Canadian order for 1,500 S&W revolvers was placed 21 August 1915, with a second order for 1,000 placed "shortly thereafter" ..... though only the first 850 pistols from that second order were actually delivered in 1915. (My own S&W Hand Ejector was apparently from this second order - the S&W letter I obtained for it states that it was shipped to the "Canadian Government" on 24 December 1915 - and accordingly may be one of the 150 revolvers not actually received until early in 1916.)
Two subsequent orders made up the balance of the Canadian S&W purchases - 6,000 ordered in late 1916 and another 6,000 in 1917. Clive Law apparently did not discover any complete range of S&W serial numbers, but he includes a list of .455 S&W revolvers in the Royal Canadian Navy Esquimalt Depot as of October 1944, ranging from a low of 3889 (presumably First Model) to a high of 85910. Any RCN-issue revolver would likely have Navy markings, I believe.) In any event, it seems logical to assume that the WWI-purchase serial number range would include Hand Ejector revolvers manufactured from 1915 through 1917 (or perhaps even early 1918). Unfortunately, my reference library is sadly lacking in the S&W area (haven't filled in that gap because I only have my .455 Hand Ejector and an early WWII Canadian-purchase .38 Military & Police revolver) and I'm not aware of any online postings of S&W serial number ranges. Perhaps some other CGN membe has this information avaialable.
FWIW, my late-1915 .455 S&W Hand Ejector revolver is s/n 33169 .....
COLT NEW SERVICE REVOLVERS:
As you likely know, the 943 Colt "New Service" revolvers purchased by the Government in 1900 for issue to later Boer War contingents were chambered in .45 Colt, the same as the Model 1878 revolvers, to simplify ammunition supply. (This despite the statement in the Canadian War Museum online presentation regarding the Boer War that the New Service revolvers were .455 - the error has been brought to their attention but they have never corrected it.)
The extensive research by Clive Law for his "Canadian Military Handguns, 1855 - 1985" turned up a reference to purchase of 70 more .45 Cal. New Service revolvers in 1915 (i.e. after the Colt 1911's had been acquired) possibly because the initial Mobilization Orders were apparently worded that ".45 Calibre revolvers" were to be issued to certain specified NCO's (.... a later, amended Scale of Issue specified Model 1911 pistols.) His research would indicate that no record exists of any .455 cal. Colt New Service revolvers being purchased by the Canadian Government for military service. However, he does list a total of twenty .455 cal. Colt revolvers registered to the Royal Canadian Navy as of April 1935, in the s/n range 11108 through 11201. (As stated above, I'd expect any Navy-issue revolver to be so marked.) A further 600 .45 cal. New Service revolvers were subsequently acquired during WWII for the Royal Canadian Navy - 300 in May 1940 and 300 in May 1941 - and .45 Colt cartridges were definitely available in the Canadian supply system during WWII -
Any other .455-chambered Colt New Service revolvers purchased by Canada would likely have been for issue to the RNWMP - that model and calibre was adopted as the official sidearm of the Mounted Police in 1904, and 700 revolvers in that calibre were shipped to Regina in September of that year, with another 650 being acquired in 1913 and 1914. Beginning in 1919, the Colt New Service revolvers for the Mounted Police were acquired directly from Colt (rather than from Canadian suppliers) and were chambered in .45 Colt. With the 1920 merger of the RNWMP and the Dominion Police to form the RCMP, in an effort to simplify ammunition supply logistics it was decreed that the .455 revolvers would remain in service in the West and North (i.e. the original NWMP jurisdiction) and the .45 revolvers would be issued from the Lakehead east .....
I believe that the serial numbers of all RNWMP and RCMP Colt New Service revolvers are known .... and are listed in "Arms & Accoutrements of the Mounted Police, 1873 - 1973". In any event, any Mounted Police-issue Colt New Service should bear Force markings on the rear or bottom of the grip strap - either NWMP (because the first revolvers were received before new stamps were available to the armourers) or RNWMP, M.P., or the fused MP.
Having said all of the above, the fact that a .455 Colt New Service revolver lacks any Canadian military or Mounted Police markings, or other such provenance, does not rule out military service as the personal sidearm of a Canadian officer .... The expectation was that their personal sidearm would be a serviceable and reliable piece chambered for an "issue" cartridge, and .455 definitely satisfies the chambering requirement. (For example, I have a 1916-dated .455 Webley MkVI revolver- which was definitely never a Canadian "military issue" model - that is engraved on the backstrap with the identity of a young Canadian officer .... "LT. S.W. SEAGO" .... I have obtained Lieut. Seago's entire Canadian Expeditionary Force service record.) However, if the firearm is not engraved with a traceable owner's name, and any other such provenance is lacking, proving Canadian military service is likely impossible.
.
